OoMesKoO

Hey guys. Im pretty new to this forum, and pretty new to lexus's in general. About a week ago my CL light popped on. I had it checked out, and found it to be an 02 sensor. At the time there were no symptoms, nothing was wrong but the light. I figured it was okay to drive. But then day by day it got worse, lots of hesitation, no power when I accelerate, loud noise coming from from of exhaust. Now today, there is literally 0 power. I cant get it to go over 15mph, and the noise from the engine/exhaust is insanely loud. At idle, you can barely hear the engine. I went again and had the CL code checked out, because I didnt remember if it was bank 1 sensor 1 or 2 that was bad. Now I went back, and now the code is p0240, and the guy is telling me I now need a Cat. converter. Has this happened to anyone before?

Debonair

That sounds correct if you are having noise from the exhaust. The Cat could have fallen apart and blocked the exhaust.

P0240 does not appear to be a valid Diagnostic Trouble Code for the 2nd Gen GS's. Its probobly a P0420 which is Catalyst System Efficiency Bellow Threshold. This is caused by:

1.Exhausy gas leak
2.Faulty O2 sensor
3.Faulty catalytic converter

And for the record its called a CEL (Check Engine Light) or MIL (Malfunction Indicator Lamp) depending on who you ask.

CL is for ClubLexus,

OoMesKoO

Thank you for your reply. I went and disconnected the battery for about an hour to see what happens... For the first minute, maybe 2... it sounded great. Then slowly it got worse and worse, then right back down to no power, horrible noise from exhaust/engine and then 5 mph. If I went and gave it 60-80% gas, it would drop rpms and do nothing. :\ Although, whats weird now is that the CEL is no longer on? Is there any way to test the 02 sensors, or the CAT to eliminate one or the other?

1UZJAY

Remove the MAF sensor and clean it out with the MAF sensor spray; its in a gold/black botte at any auto parts store. Make sure to let it dry and remove your battery cables when doing this.

Clean out your throttle body maybe not the entire thing but just around the intake side; and while you're there go ahead and check your spark plugs for good measure.

Remove the o2 sensor if you can and clean with some alcohol or o2 sensor cleaner and then reconnect the terminals and report back.

Also make sure your fuel pump hasn't failed; easy just turn your key and do not turn on your car you'll hear the fuel pump 'prime' a bit under the hood and then next open your gas tank and put your ear next to it and you should here it 'whirring' or 'priming' as well.

Generally also most OBD scanners will not pickup the exact codes that are occurring. You'll need to get it done on a snap on diag machine or at the dealer; some shops have these computers so just check around.

Hope this helps.

OoMesKoO

Also... I just noticed this as well. I have an aftermarket Tanabe cat-back. Usually its a pretty nice sounding, kind of loud exaust. Even at idle it has a nice tone. I started the car and noticed I hear nothing. I walked to the back and noticed I have NO exhaust pressure whatsoever. :\

Debonair

Good or bad, O2 sensors make no noise. So I would imagine you have a bad Cat or a bad Cat and O2. The O2s can be tested with a multimeter, the Cat with a pressure gauge. If the CEL went off more then likely the O2 is ok. The Cat is the bigger ($$$) job of the two so I would start there and then replace the O2 if it is still bad sets a DTC.

OoMesKoO

Is there any way you can point me in the right direction of doing this?

GS4_Fiend

iTrader: (22)

go get the exhaust leak first...

TonyHC

Judging from this statement, I would assume you have some sort of blockage or clogged cat.

tinman

Sure sounds like a blockage in the exhaust. Replacing the cat isn't uncommon in that scenario. The pressure is building up in the exhaust, causing the noise and poor performance.

GS_Louis

iTrader: (9)

I second this. Get a new cat.

slickgt1

iTrader: (1)

I second the Maf. I had this issue on my car. Had a lot of codes. Search for my name, there is a big thread I did a while back about it. Was told it was cat, 02, everything. Was the Maf. Didn't get any codes for the Maf either BTW.

slickgt1

iTrader: (1)

I think its the maf even more, because you reset the ECU, and it was fine for a bit. If it was a clogged cat, it would not be fine at all. At startup our computers use default maps, this is for cold-start. Then the computer starts to read the MAF, ECT, and a bunch of other stuff, this is when your car bugs out. I'd go with the maf, they are not lifetime, and need replacements. Clean it first, and see if that helps any. Although no amount of cleaning did anything for my maf.

TonyHC

Things expand when they heat up. Ive seen failed cats become more restrictive as it gets hotter.

I say look into both the Cat and the Map and go from there.

Debonair

I have never seen or heard of a MAF causing exhaust noise or lack of exhaust pressure. MAF cleaner is a few bucks so it may be worth trying it before getting the CAT. I personally doubt it could be responsible for all the symptoms you have.